As shown in FIG. 10, a conventional piezoelectric device of this type thus available includes outer housing 1, lead wires 2 each having one end disposed on bottom surface 1a of outer housing 1, and piezoelectric oscillator 3 retained by the other ends of lead wires 2, wherein terminals 3a of piezoelectric oscillator 3 and lead wires 2 are respectively electrically connected to each other by, for example, metal bumps 4.
In the conventional piezoelectric device having the structure, an alternate-current signal outputted from, for example, IC, is transmitted to piezoelectric oscillator 3 by way of lead wires 2 and metal bumps 4, and piezoelectric oscillator 3 is thereby driven. Then, an alternate-current detection signal outputted from piezoelectric oscillator 3 travels on the same route backward, more specifically, the signal is transmitted to the IC or the like by way of metal bumps 4 and lead wires 2.
An example of the conventional art documents relating to the present application is Patent Document 1.
The conventional problem of such a conventional piezoelectric device was difficulty in reducing its vertical height.
In other words, in the conventional structure, since metal bumps 4 are formed by a bonding process between lead wires 2 and terminals 3a of piezoelectric oscillator 3, it was difficult to reduce the thickness of metal bumps 4, therefore, leading to the difficulty in reducing the vertical height of the device.    Patent Document 1: Unexamined Japanese Patent Publication No. 2007-167854